Manufacture of artificial threads from solutions of cellulose.



UNTTE. STATES PATENT UIRTTCE.

Specification of Letters Patent.

Patented July 25, 1905.

Application filed April 4,1905. Serial No. 253,858.

To all whom, it may concern:

Be it known that I, RUDoLF LINKMEYER, textile engineer, a subject of theEmperor of Germany, residing at Herford, in the Empire of Germany, haveinvented certain new and useful Improvements in the Manufacture ofArtificial Threads from Solutions of Cellulose, of which the followingis a specification.

It is known that artificial threads presenting the luster of silk may beproduced by effecting the solution of cellulose in ammoniacal oxid ofcopper and in then precipitating the cellulose from its solution.Cellulose cannot, however, be readily dissolved directly in largequantities in ammoniacal oxid of copper in such a manner that thesolution may present a degree of concentration sufiicient to permit ofthe precipitation. Solution may in certain cases require eight days.Numerous processes have already been suggested for facilitating thesolution, the greater number of these processes being based upon theenergetic action of fixed alkalies before the solution with a view toproducing a previous dehydration of the cellulose. All these proc essespresent serious defects. In particular they are complicated by the factthat the previous treatment and the solution of the cellulose must beeffected with difierent chemical agents.

The process which forms the subject of the present invention obviatesthese defects, the preliminary treatment and dissolving the cellulosebeing effected with the same reagents employed in solutions only thedegree of concentration of which differs.

This process consists, broadly, in first of all producing in afirst weakbath of ammoniacal oxid of copper a swelling of the fibers and a depositof oxid of copper upon them and in then cfi'ecting solution in aconcentrated solution of ammoniacal oxid of copper. In this manner asolution is obtained the very pronounced viscosity of which is extremelyadvantageous for spinning.

It has been found that the solution of the cellulose is effected veryefficiently if the cotton, bleached or boiled for some hours, is firstof all placed, either in a dry or humid condition, in a weak bath ofammoniacal oxid. of copper, to which may be added with advantage a smallquantity of caustic soda. This first bath serves to soften, swell, anddisaggregate to some extent the fibers and to fix upon them the oxid ofcopper dissolved by the ammonia. The fibers then dissolve speedily andreadily in a concentrated solution of ammoniacal oxid of copper. Byproceeding in this manner the conversion of the cellulose intooxycellulose or the hydration of the fibers is avoided. Further, thesuccess of the solution depends less upon the temperature than upon theother processes. Solution takes place equally well at 10 to 15Centigrade as at a lower temperature.

The process may be applied as follows: About seven grams of cotton freedfrom grease or bleached are placed in, say, one h undred and fifty toone hundred and eighty cubic centimeters of ammoniacal oxid of coppercontaining about twelve grams of copper and ninety grams of ammonia perliter and to which there has previously been added, say, six cubiccentimeters of caustic soda at L0 to 50 Baum. After remaining for two tothree hours or longer in this bath the fibrous material is removed andfreed by pressure from the liquid in excess, and it is then dissolved inone hundred grams of ammoniacal oxid of copper containing, say, sixteento eighteen grams of copper and two hundred grams of ammonia per liter.In this manner a thick solution is speedily obtained which may bediluted with water. After careful filtration this solution is ready forconversion into threads of artificial silk by an appropriate treatment.

What I claim, and desire to secure byLetters Patent of the UnitedStates, is

1. A process for the solution of cellulose in ammoniacal oxid of copper,consisting in placing the cellulose first of all in a weak solution ofammoniacal oxid of copper and then

